Extending Trendline by Small Values

**RaptorDan** · 09-21-2013, 12:54 PM

I am trying to extend a linear trendline for a graph of molarity vs absorbance. Unfortunately, excel will only let me extend the trendline by 0.5 forward or backward, and the values that I am working with are much smaller. The units that I am working with are 0.001, and extending the trendline by 0.5 zooms out from my values so far that they cannot be seen. Is there any way that I can extend the trendline by smaller values than 0.5? Thanks for the help.

**RaptorDan** · 09-21-2013, 11:00 PM

Bump. I could really use some help with this...

**MrShorty** · 09-21-2013, 11:15 PM

Can I assume you are using the chart trendline feature to generate the trendline? I find that I never use the chart trendline feature. Instead, I prefer to generate regressions using the LINEST() function http://office.microsoft.com/en-us/ex...005209155.aspx

Along the same lines, you can also use the TREND() function http://office.microsoft.com/en-us/ma...081.aspx?CTT=1

If you are intimidated by these worksheet functions, the easiest approach might be to display the equation on the chart (be sure to use enough decimal places), hand enter the coefficients of the equation in the spreadsheet, then calculate the extension in the spreadsheet.

However you do it, you can show the extension on the chart by plotting the trendline as calculated in the spreadsheet. Then you will have the flexibility you need to extend the trendline in whatever increment you want to use.